1. Field of the Invention
This invention relates generally to electrical insulating bushings and, more particularly, to such bushings having interchangeable conductors for various current ratings.
2. Description of the Prior Art
The apparatus bushing industry has conventionally used a single current-carrying element as the electrical path through a bushing, such being a result of restrictions imposed by skin effect. The non-uniformity of current distribution due to the frequency of the current is called "skin effect". The net result of the skin effect for 60 Hertz was to limit the practical conductors to a small diameter metal rod up to approximately 1 inch diameter, or a metal tube with a wall thickness of approximately one-half inch. As the current capacity requirements increased, a larger diameter tube was employed to provide a larger cross section for the current path.
Associated with the foregoing is the problem of holding in stock a supply of bushings for the several and various current ratings required by electrical customers. As a result, a costly procedure for maintaining and accounting for bushings was required for the varying current ratings.